Effect of tumour necrosis factor-alpha on proliferation, activation and protein synthesis of rat hepatic stellate cells.
OBJECTIVE
Hepatic stellate cells represent the principal matrix-synthesising cells of damaged liver and are targets of a number of cytokines currently under investigation. The study analyses the effects of tumour necrosis factor-alpha and interferon-gamma on proliferation, "activation" and protein synthesis of hepatic stellate cells.


METHODS
Primary cultures of hepatic stellate cells were exposed to tumour necrosis factor-alpha and interferon-gamma. Cell proliferation was studied by 3H-thymidine and bromo-deoxy-uridine incorporation. Protein synthesis was analysed using immunoprecipitation, Western- and Northern blotting techniques.


RESULTS
Proliferation of hepatic stellate cells was reduced by tumor necrosis factor-alpha and interferon-gamma, while "activation" of hepatic stellate cells as assessed by expression of smooth muscle alpha-actin and of TGF-beta/activin type I receptor was induced by tumour necrosis factor-alpha but downregulated by interferon-gamma. Tumour necrosis factor-alpha increased the synthesis of distinct extracellular matrix proteins, particularly of fibronectin and tenascin, but decreased collagen type III expression. In contrast, interferon-gamma reduced the synthesis of all connective tissue proteins tested. Among the protease inhibitors, interferon-gamma induced C1-esterase inhibitor synthesis, while tumour necrosis factor-alpha stimulated plasminogen activator inhibitor type 1 production.


CONCLUSIONS
Tumour necrosis factor-alpha and interferon-gamma decrease proliferation of hepatic stellate cells, while "activation" of hepatic stellate cells and synthesis of proteins involved in matrix metabolism are regulated in a differential, cytokine-specific manner, suggesting that both cytokines play an important role in liver repair.
Knittel
T
T
Department of Internal Medicine, University of Göttingen, Germany.
Müller
L
L
Saile
B
B
Ramadori
G
G
D017667:Adipocytes / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D002455:Cell Division / Q000187:drug effects; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis*; D007371:Interferon-gamma / Q000494:pharmacology; D008099:Liver / Q000166:cytology / Q000187:drug effects*; D011480:Protease Inhibitors / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D016326:Extracellular Matrix Proteins; D011480:Protease Inhibitors; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma